The Mechanical 0-30 PSI Differential Pressure Murphygage Oil Sealed without Contact 20DPG-OS-30 by Murphy is a diaphragm-actuated, differential pressure-indicating gage. Gauge is intended to monitor and indicate oil, fuel or water filter restriction and can reduce the risk of dangerously high pressure which may rupture the filter, resulting in contaminants entering the system. The 20DPG mechanism is enclosed in a steel case coated to resist corrosion and it features a polycarbonate, break-resistant lens and a polished, stainless steel bezel to help protect this rugged, built-to-last instrument.